Research On Optimal Control Strategy Of Photovoltaic Microgrid

With the continuous development of industry and the growing power demand of the people,the research and development of clean and sustainable energy has become an important direction of electric power development,among which solar power generation technology has become one of the hotspots of new energy research and development because of its unique advantages.Traditional industrial power generation is generally generated in parallel through synchronous generators.Because the traditional synchronous generators have good dynamic characteristics,the traditional power system has high stability.However,the microgrid system based on distributed generation is generally connected to the microgrid inverter,and its interface characteristics are quite different from the traditional power generation system.With the large-scale application of photovoltaic microgrid system,there are more and more problems in the power system.The photovoltaic microgrid system has better interface characteristics by simulating the dynamic performance of the traditional synchronous generator,which is of great significance to the development of the photovoltaic microgrid.First of all,this thesis introduces the main topology structure and working principle of photovoltaic microgrid.Photovoltaic microgrid is mainly composed of photovoltaic unit,microgrid inverter and energy storage system,and then its control strategy is analyzed in detail.the established photovoltaic microgrid platform is verified by simulation.The dynamic performance of traditional synchronous generator can be reflected by its second-order transient model.The technology of virtual synchronous generator(VSG)is established by simulating its interface characteristics.The transient characteristics and stability of system parameters are analyzed,and the effects of virtual inertia and damping coefficient under different charged states of energy storage are deduced.The transfer function is established by small signal analysis,and the boundary of parameters is obtained.In this thesis,a single-objective parameter optimization control strategy based on VSG algorithm is proposed,which can not only make the photovoltaic microgrid system present the interface characteristics of the traditional synchronous generator,but also make the system run under the optimal parameters.Based on the VSG algorithm research,by considering the realization of multi-objectives in the photovoltaic microgrid,combined with the multi-objective VSG control strategy,the photovoltaic microgrid is controlled,so that the photovoltaic microgrid can achieve the purpose of multi-objectives,and achieve the flexible control of the microgrid.The system simulation model is established in MATLAB/Simulink.The simulation results show that:(1)the photovoltaic microgrid system based on VSG algorithm has virtual inertia and virtual damping,avoids the impact of system power and frequency,and improves the dynamic characteristics of the system;(2)the optimization of VSG algorithm parameters is realized by longicorn cattle optimization algorithm,and the system has high stability and transient characteristics.(3)the photovoltaic microgrid control strategy based on VSG multi-objective optimal control technology not only realizes the reliable operation of photovoltaic microgrid,but also works under high performance.